The invention relates to a process for recovering monomeric units of a nylon from carpet material.
It is known that monomeric units of a nylon can be recovered from carpet material, in particular from waste carpet material.
WO-A-9720813 describes a depolymerisation process in which caprolactam is recovered from nylon-6 containing carpets. It is described that carpets are size reduced by mechanical treatment, after which depolymerization of the nylon is effected.
U.S. Pat. No. 5,169,870 discloses a process for the recovery of caprolactam from nylon-6 carpet in which a large portion of the backing is removed from the carpet in a mechanical separator before it is fed to a depolymerization reactor.
EP-A-728565 describes a process for reclaiming polymeric fibres from carpeting using a series of mechanical steps. It is described that a carpet mixture can be obtained which preferably contains between about 75 to about 85 wt. %. of nylon particulates. It is described that the product obtained is in particular suitable for the process described in U.S. Pat. No. 5,169,870. In the process of EP-A-728565 many mechanical steps are used. This is disadvantageous in view of operating and investment costs.
The references cited above disclose processes in which the carpets used as a starting material have a nylon content of about 50 wt. % or higher. However, a significant fraction of the carpets available for recycling, in particular carpets for the European market, contain between 15 to 35 wt. % nylon.
It is an object of the invention to provide an efficient process for recovering monomeric units of a nylon from carpet carpet material which contains between 15 to 35 wt. % nylon.